The invention relates to a process for cleaning an adhesive applicator with driven adhesive rollers, which can be rotated around vertical axes and which together with a housing, which is positioned at these adhesive rollers and whose side edges rest or almost rest against the adhesive rollers, forms an adhesive chamber.
This type of adhesive applicator is disclosed in the DE 196 34 594 A1. Adhesive applicators tend to get dirty and encrusted with adhesive residues so that it is necessary to clean the adhesive applicator at regular intervals and in particular before or after operating breaks. The cleaning of the adhesive applicator disclosed in the DE 196 34 594 A1 is facilitated by removing easily and rapidly the housing for the purpose of cleaning the adhesive applicator. However, it is unavoidable with the prior art adhesive applicator that a relatively time-consuming manual cleaning is necessary.
Therefore, the object of the invention is to provide a process of the aforementioned type that facilitates automatic cleaning of the adhesive applicator.
The invention solves this problem in that the adhesive is removed first from the adhesive chamber, and then wash water is introduced into the adhesive chamber and in that the wash water is displaced into turbulent flows by driving the adhesive rollers alternatingly in opposite directions to each other and then drained after a fixed cleaning period.
Before cleaning, the adhesive can be removed from the adhesive chamber by detaching a seal, for example, a plug, which is arranged in the floor of the adhesive chamber so that the adhesive that is still present in the adhesive chamber drains and is caught in the basin, arranged directly below the outlet opening. Then the cleaning begins by introducing the wash water.
To drain the adhesive that is still present in the adhesive chamber, the adhesive rollers can also be driven in the counter direction of rotation relative to the adhesive application. After this process the adhesive that is still present in the adhesive applicator or the adhesive chamber is drained in a first step by driving the adhesive rollers in the opposite direction, thus in a direction that is opposite to their direction of rotation relative to the application of the adhesive. Driving in this opposite direction causes the adhesive that is still present in the adhesive chamber to issue from the gap between the adhesive roller and the side edge of the housing, which is not positioned snugly against the adhesive roller or is provided with a doctor blade. The adhesive, issuing in a short period of time from the adhesive chamber, is caught in a basin situated below the adhesive applicator and is drained from this basin in the conventional manner. As soon as the adhesive that is still present is drained from the adhesive applicator, the wash water is introduced into the adhesive chamber. This wash water is displaced into turbulent flow by driving the adhesive rollers alternatingly in opposite directions to each other. The wash water runs by itself or by means of counter rotating adhesive rollers out of the adhesive chamber and is caught in the basin located below the adhesive applicator and is drained.
The cleaning effect can be significantly increased by driving the adhesive rollers at different velocities during the cleaning phase.
Furthermore, it is expedient to move the cleaning rollers apart temporarily during the cleaning phase in order to open the metering gap located between these two cleaning rollers.
The draining of the adhesive and the subsequent cleaning with wash water is done expediently according to a given program with fixed times, during which the adhesive is drained, the wash water is introduced and the adhesive rollers are driven in opposite directions. The individual phases of the wash procedure are controlled expediently by an electronic controller and/or a microcomputer.
A device to carry out the process of the invention is characterized according to the invention in that the adhesive chamber, which has a solenoid operated valve controlled by an electronic controller or a microcomputer, is provided with a line to feed in the wash water, and that the speed and the adhesive rollers"" direction of rotation and optionally their motion can be controlled by the electronic controller or the microprocessor in order to enlarge or decrease the metering gap between the adhesive rollers.